From: Patrick Roemer <sangamon@...>
Date: 2005-09-21T23:16:39+09:00
Subject: Re: Continuation - where does it continue

Responding to michelemendel@gmail.com:

> Why does the following code print the line "doing other stuff" twice?
> 
> def cc
>     puts "do A"
>     puts "----> 1. #{caller}"
>     callcc { |cont| return cont}
>     puts "----> 2. #{caller}"
>     puts "do B"
> end
> 
> puts "calling cc"
> cont = cc()
> puts "doing other stuff"
> cont.call() if cont
> puts "end of work"
> puts

The continuation 'continues' from exactly the state where it left off: 
It starts after the callcc call, after returning from the cc method it 
continues one 'stack frame'[1] deeper after the cc() call, just as in 
normal execution - it won't 'jump back' to the code position after the 
continuation call.

Best regards,
Patrick

[1] Java lingo, don't know what it's called in Ruby